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ashramof1-deactivated20201019

Prayer

However madly the circumference of your life tilts and spins, may you never lose that still, silent, untouched centre that has been with you since you first arrived on this planet

and got shackled with a name.

earthstory

Hard to believe some of these landscapes are real. Original caption:

The north coast of Spain is a wild and beautiful place, where the sea meets the rocks under big skies. Alister benn and Juanli Sun have a long relationship with this landscape and in this short film show their passion for the sea.

compoundchem

‪Wildfires are currently raging in a number of countries. It’s not just the flames that pose a risk to life; the combustion products can cause problems too: https://cen.acs.org/articles/96/i3/Periodic-graphics-chemistry-wildfires.html

expressions-of-nature

Iceland by Fernando Puente

runta1210

出会い

online sales http://alice-books.com/item/show/4562-5

fuckyeahfluiddynamics

For rocket combustion and other applications, like watering your lawn with a hose, a stream of fluid may need to be broken up into droplets. While simply spraying a liquid jet will make it break up, waving that jet back and forth will break it up faster. A recent study simulated this problem numerically to determine the exact mechanisms driving that break-up. The researchers found two major culprits.

The first is a Kelvin-Helmholtz, or shear-based, instability. When a jet leaves the nozzle, there’s friction between it and the comparatively still air surrounding it. This creates tiny ripples in the surface that eventually grow into the distortions we can see, and it’s found in all jets, regardless of their side-to-side motion.

The second culprit, which is only found in the oscillating jet, is a Rayleigh-Taylor instability. By moving the jet side-to-side, you’re driving the dense liquid into less dense air, which creates a different set of disturbances that also help break up the jet. The final result: swinging the jet side-to-side breaks it into smaller droplets faster. (Image and research credit: S. Schmidt et al.)

fuckyeahfluiddynamics

When I was a child, my father would take me trout fishing, and I spent hours marveling from the riverbank at the trouts’ ability to, seemingly effortlessly, hold their position in the fast-moving water. As it turns out, those trout really were swimming effortlessly, in a manner demonstrated above. The fish you see here swimming behind the obstacle is dead. There’s nothing powering it, except the energy its flexible body can extract from the flow around it.

The obstacle sheds a wake of alternating vortices into the flow, and when the fish is properly positioned in that wake, the vortices themselves flex the fish’s body such that its head and its tail point in different directions. Under just the right conditions, there’s actually a resonance between the vortices and the fish’s body that generates enough thrust to overcome the fish’s drag. This means the fish can actually swim upstream without expending any energy of its own! The researchers came across this entirely by accident, and one of the questions that remains is how the trout is able to sense its surroundings well enough to intentionally take advantage of the effect. (Image and research credit: D. Beal et al.; via PhysicsBuzz; submitted by Kam-Yung Soh)